As the segment of the population advanced in age increases in society, the number of patients with osteoporosis is rapidly increasing. The diagnostic criteria and therapy for osteoporosis have been earnestly investigated. Bones become friable and weak in the osteoporosis patient. Pressure fracture of the spine and limb fracture causing pain or dysfunction to the patient easily occur by a trifle action or weak impact. Osteoporosis not only imparts pain to the patient but often makes the patient bedridden, leading to heavy burdens upon persons attending to the patient and to society supporting medical expenses.
Various pathophysiologies of osteoporosis have been suggested. Osteoporosis in women rapidly increases after menopause and the early onset of osteoporosis is observed in ovariectomy women. Accordingly, a decrease in female hormones, especially estrogen, is thought to be the important cause of osteoporosis. In fact, the occurrence of osteoporosis in women is several times that in men. Also, osteoporosis in women occurs earlier than in men and its occurrence rapidly increases around menopause. Osteoporosis brought about by the decrease in estrogen is the leading cause of the disease and is one of the diseases for which an appropriate therapeutic agent has been sought. The first choice for the treatment of osteoporosis in Europe and America is estrogen replacement therapy to replenish estrogen. However, estrogen causes undesirable side effects such as metrorrhagia and mammary hypertrophy. Estrogen replacement therapy also has a high risk of inducing mammary carcinoma. Therefore, estrogen replacement therapy in Japan is not preferred unlike as in Europe and America.
Since the estrogen replacement therapy against osteoporosis may have adverse side effects, a drug with a much higher safety profile than estrogen replacement therapy and which can be administered for a long term is needed.
The inventors of the present invention have found that an extract from inflammatory rabbit skin inoculated with vaccinia virus has superior effects for treatment of osteoporosis accompanied by a decrease in estrogen, such as maintaining bone volume, trabecular connectivity and bone strength.